U.S. patent number 9,102,103 [Application Number 11/699,653] was granted by the patent office on 2015-08-11 for thermoplastic composite parts having integrated metal fittings and method of making the same.
This patent grant is currently assigned to THE BOEING COMPANY. The grantee listed for this patent is James R. Fox, Alexander M. Rubin, Randall D. Wilkerson. Invention is credited to James R. Fox, Alexander M. Rubin, Randall D. Wilkerson.
United States Patent |
9,102,103 |
Fox , et al. |
August 11, 2015 |
Thermoplastic composite parts having integrated metal fittings and
method of making the same
Abstract
Thermoplastic composite parts having integrated metal fittings
are manufactured using a continuous compression molding process.
Automated equipment or hand lay-up are used to collate composite
material plies and metal fittings into a multi-layer stack. Each
stack contains all plies, including ply build-up areas, tacked in
the proper location to maintain orientation and location. Multiple
lay-ups may be cut from each stack. The lay-ups are placed in
tooling containing part features and are continuously fed through a
performing station where the lay-ups are preformed into the
approximate shape of the finished part. Following pre-forming, the
tooling is moved incrementally through a consolidation station
where a compression press presses successive sections of the
tooling to form a single integrated thermoplastic composite
laminate part having integrated metal fittings, which may include
areas of differing thickness.
Inventors: |
Fox; James R. (Florissant,
MO), Wilkerson; Randall D. (O'Fallon, MO), Rubin;
Alexander M. (St. Louis, MO) |
Applicant: |
Name |
City |
State |
Country |
Type |
Fox; James R.
Wilkerson; Randall D.
Rubin; Alexander M. |
Florissant
O'Fallon
St. Louis |
MO
MO
MO |
US
US
US |
|
|
Assignee: |
THE BOEING COMPANY (Chicago,
IL)
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Family
ID: |
39167736 |
Appl.
No.: |
11/699,653 |
Filed: |
January 29, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070175573 A1 |
Aug 2, 2007 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11347122 |
Feb 2, 2006 |
7807005 |
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11584923 |
Oct 20, 2006 |
8333858 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B
3/085 (20130101); B29C 70/86 (20130101); B32B
27/286 (20130101); B29C 70/50 (20130101); B29D
99/0007 (20130101); B29C 70/34 (20130101); B32B
27/288 (20130101); B29C 70/545 (20130101); B32B
15/08 (20130101); B32B 27/285 (20130101); B29C
70/885 (20130101); B29C 70/525 (20130101); B32B
27/08 (20130101); B32B 2605/003 (20130101); B29K
2101/12 (20130101); Y10T 156/1002 (20150115); B32B
2605/18 (20130101); B32B 2262/101 (20130101); B32B
2262/106 (20130101) |
Current International
Class: |
B29C
70/34 (20060101); B32B 27/28 (20060101); B32B
27/08 (20060101); B29C 70/50 (20060101); B29C
70/52 (20060101); B29C 70/54 (20060101); B29C
70/86 (20060101); B29C 70/88 (20060101); B29D
99/00 (20100101); B32B 15/08 (20060101); B32B
3/08 (20060101) |
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Primary Examiner: Schatz; Christopher
Attorney, Agent or Firm: Yee & Associates, P.C.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent
application Ser. No. 11/347,122, filed Feb. 2, 2006 now U.S. Pat.
No. 7,807,005, and of U.S. patent application Ser. No. 11/584,923,
filed Oct. 20, 2006 now U.S. Pat. No. 8,333,858.
Claims
What is claimed is:
1. A method of manufacturing a part having a joint between a
polymeric composite laminate and a metal fitting, the method
comprising forming a lay-up by positioning a metal fitting adjacent
to a traverse edge of a stack comprising plies of a composite
material tacked together such that at least part of an edge of the
metal fitting contacts at least part of the edge of the stack;
placing the lay-up between two metal tools; feeding the lay-up
through a continuous compression machine; consolidating the layup
to form the joint, wherein consolidating is performed by the
continuous compression machine, wherein feeding the lay-up through
a continuous compression machine comprises feeding the metal tools
and the lay-up into the continuous compression machine.
2. The method of claim 1, further comprising introducing a
thermoplastic film between the metal fitting and one of the
plies.
3. The method of claim 1, wherein the plies are tacked together at
multiple locations by heating or ultrasonic welding.
4. The method of claim 1, further comprising: preforming the lay-up
into the approximate shape of the part.
5. The method of claim 1, wherein the composite material includes a
matrix resin component having a free flowing temperature, and the
method further comprises: preforming the lay-up into the
approximate shape of the part; and heating the preformed lay-up to
at least the free flowing temperature of the matrix resin component
of the composite material before feeding the lay-up through the
continuous compression machine.
6. The method of claim 1, wherein the method further comprises:
preforming the lay-up into the approximate shape of the part, and
wherein the consolidating includes pressing at least one of the
metal tools against the preformed lay-up to impart features of the
tool on the preformed lay-up.
7. The method of claim 1, wherein the consolidating is performed by
incrementally moving the lay-up through the press.
8. The method of claim 1, wherein the polymeric composite laminate
is a thermoplastic composite laminate.
9. A method of manufacturing a part comprising a part having a
joint between a polymeric composite laminate and a metal fitting,
the method comprising: forming a lay-up by positioning a metal
fitting adjacent to a traverse edge of a stack comprising plies of
a composite material tacked together such that at least part of an
edge of the metal fitting contacts at least part of the edge of the
stack; placing the lay-up between two metal tools; feeding the
lay-up with the two metal tools through a continuous compression
machine; and consolidating the layup, wherein consolidating
comprises applying pressure to the two metal tools using press
platens of the continuous compression machine.
10. The method of claim 9, further comprising: cleaning the surface
of the metal fitting; and applying a bonding primer to the cleaned
surfaces of the metal fitting.
11. The method of claim 10, further comprising: applying a resin
film to the primed surfaces of the metal fitting.
12. The method of claim 9, further comprising: preforming the
lay-up into the approximate shape of the part.
13. The method of claim 9, wherein consolidating includes pressing
the two metal tools against the lay-up and wherein at least one of
the two metal tools imparts features of the at least one tool on
the lay-up.
14. A method of manufacturing a part comprising a polymeric
composite laminate and an integrated metal fitting, the method
comprising: positioning a first stack adjacent a second stack such
that at least a part of a first traverse edge of the first stack
contacts at least a part of a second traverse edge of the second
stack, the first stack comprising a first number of plies of a
composite material tacked together and the second stack comprising
a second number of plies of a composite material tacked together;
positioning a metal fitting on at least a portion of the first
stack and on at least a portion of the second stack to form a
lay-up; placing the lay-up between two metal tool members; feeding
the lay-up with the two metal tool members through a continuous
compression machine; and consolidating the layup, wherein
consolidating comprises applying pressure to the two metal tool
members using press platens of the continuous compression
machine.
15. The method of claim 14, further comprising: cleaning the
surface of the metal fitting; and applying a bonding primer to the
cleaned surfaces of the metal fitting.
16. The method of claim 15, further comprising: applying a resin
film to the primed surfaces of the metal fitting.
17. The method of claim 14, further comprising: preforming the
lay-up into the approximate shape of the part.
18. The method of claim 14, wherein consolidating includes pressing
the two metal tools against the lay-up and wherein at least one of
the two metal tools imparts features of the at least one tool on
the lay-up.
19. A method of manufacturing a part comprising a polymeric
composite laminate and an integrated metal fitting, the method
comprising: positioning a first stack adjacent a second stack such
that at least a part of a first traverse edge of the first stack
contacts at least a part of a second traverse edge of the second
stack to form a joint, the first stack comprising a first number of
plies of a composite material tacked together and the second stack
comprising a second number of plies of a composite material tacked
together; positioning a metal fitting over the joint to form a
lay-up; placing the lay-up between two metal tool members, one of
the two metal tool members including a pocket having a shape
matching that of the metal fitting; feeding the lay-up with the two
metal tool members through a continuous compression machine; and
consolidating the layup, wherein consolidating comprises applying
pressure to the two metal tool members using press platens of the
continuous compression machine.
20. The method of claim 19, further comprising: cleaning the
surface of the metal fitting; and applying a bonding primer to the
cleaned surfaces of the metal fitting.
21. The method of claim 20, further comprising: applying a resin
film to the primed surfaces of the metal fitting.
22. The method of claim 19, further comprising: preforming the
lay-up into the approximate shape of the part.
23. The method of claim 19, wherein consolidating includes pressing
the two metal tools against the lay-up and wherein at least one of
the two metal tools imparts features of the at least one tool on
the lay-up.
24. The method of claim 19, further comprising: positioning a
second metal fitting on an opposite side of the joint prior to
placing the lay-up between the two metal tool members.
Description
TECHNICAL FIELD
This disclosure generally relates to processes for fabricating
composite material parts, and deals more particularly with a method
for making thermoplastic composite parts having integrated metal
fittings, using a continuous part forming process.
BACKGROUND
Numerous processes exist for fabricating Thermoplastic composite
(TPC) laminates. In addition to non-continuous processes such as
pressing, stamping and autoclave forming, there are continuous
processes such as extrusion, pultrusion, roll forming, and
compression molding. More recently, processes have been developed
for producing TPC parts in continuous lengths using a continuous
compression molding (CCM) process, which have varying thickness
and/or curvature along their lengths.
Adding to the challenge of manufacturing TPC laminate structures
and parts in a continuous process, is the need to attach metal
fittings to the laminate structures. Metal fittings may be used,
for example, in the aircraft industry, to attach the laminate
structures to other parts of the aircraft, or to reinforce areas of
the laminate structure requiring additional stiffness. In the past,
metal fittings were first formed as separate features, and then
joined to laminate structures using fastening devices. This
approach to adding metal fittings to laminate structures and parts
is generally not cost effective, requires additional time and
material and adds weight to the aircraft. Processes exist for
forming bonded joints between TPCs and metal fittings, however
these bonded joints must be processed in ovens or autoclaves which
limits the length of the parts that can be processed due to the
size capacity of commercially available equipment.
Accordingly, a need exists for a method for fabricating TPC
structures and parts having integrated metal fittings in a
continuous process. Embodiments of the disclosure are directed
towards satisfying this need.
SUMMARY
Embodiments of the disclosure provide a method for fabricating
thermoplastic composite laminate parts having integrated metal
fittings, using a continuous fabrication process. The parts may
have tailored and/or varying thicknesses, as well as curvature. The
process utilizes automated equipment or hand lay-up to collate
parts or components into a multi-layer stack. Each stack contains
all laminate plies, including ply build-up areas, tacked in the
proper location to maintain orientation and location. Consolidation
tooling is provided which contains all necessary part features and
is coordinated to customized multiple ply stacks to form a single
integrated composite laminate potentially having areas of differing
thicknesses. Composite part having integrated metal fittings formed
by the above method may find use in a wide variety of applications,
including, for example, automotive and aerospace applications.
In accordance with one embodiment of the disclosure, a method is
provided for manufacturing a thermoplastic composite laminate
structure having an integrated metal fitting. The method includes
the steps of: forming a lay-up including a multiple ply stack of
thermoplastic composite material and at least one metal fitting;
feeding the lay-up through a press; and, consolidating the plies
and the fitting using the press. A film of thermoplastic material
is introduced between the metal fitting and one of the plies to
improve bonding. The plies of the stack may be tacked together in
order to maintain their relative orientation during the fabrication
process. A joint between the metal fitting and the laminate
structure may take any of various forms, including a double-lap
splice, scarf, stepped lap, or rabbet, to name a few. The lay-up
containing the metal fitting is placed between tooling which is
moved continuously through pre-forming and consolidation
operations. The lay-up is preformed in the pre-forming operation
into the approximate shape of the laminate structure. Following
pre-forming, the plies and metal fitting are consolidated in a
compression press.
In accordance with another embodiment, a method is provided for
manufacturing thermoplastic composite laminate parts having metal
fittings in a continuous process. The method includes the steps of:
collating multiple plies of a thermoplastic composite material;
providing metal fittings for the parts; forming a plurality of
lay-ups, each including the collated plies and at least one of the
metal fittings; pre-forming each of the lay-ups into the
approximate shape of the part; and, consolidating the plies and the
metal fitting by incrementally moving the lay-ups through a
continuous compression molding press. The plies are configured so
as to form a joint of a chosen geometry, between the metal fitting
and laminate plies in each of the stacks. The lay-ups containing
the metal fittings are placed between tools that are configured to
impart features to the preformed lay-up during the consolidation
process. The preformed lay-ups are heated to at least the
free-flowing temperature of the matrix resin component in the ply
material during the consolidation process. The metal fittings are
cleaned and then primed before a resin film is applied to the
primed surfaces of the fitting in order to improve bonding.
According to another embodiment, thermoplastic laminate parts each
having at least one integrated metal fitting are produced by a
continuous manufacturing process. The process comprises the steps
of: forming a plurality of lay-ups, each including a tacked stack
of multiple plies of thermoplastic composite material and at least
one metal fitting; placing a set of tooling over each of the
lay-ups; continuously moving the lay-ups through a pre-forming
station; pre-forming each of the lay-ups at the pre-forming station
into the approximate shape of the part; continuously moving the
tooling with the preformed lay-ups through a press; and,
consolidating the plies in the lay-ups and the fittings by
compressing successive sections of the tooling as the tooling moves
through the press. The lay-ups may be formed by collating and
tacking the plies so that the plies are held in fixed, registered
relationship to each other, and to the metal fitting. The tooling
containing the lay-ups is moved through the press in incremental
steps so that the press consolidates successive sections of the
lay-up.
Other features, benefits and advantages of the disclosed
embodiments will become apparent from the following description of
embodiments, when viewed in accordance with the attached drawings
and appended claims.
BRIEF DESCRIPTION OF THE ILLUSTRATIONS
FIG. 1 are combined exploded and perspective illustrations of a
thermoplastic composite laminate formed in accordance with an
embodiment of the disclosure.
FIG. 2 is a perspective illustration of a conveyor table used to
form a tailored multiplayer stack.
FIG. 3 is a perspective illustration of one example of a tailored
multi-layer stack formed in FIG. 2.
FIG. 4 illustrates a pre-forming zone and a consolidating zone of a
consolidation structure used to form the thermoplastic composite
laminate of FIG. 1.
FIG. 5 is a perspective illustration of the pre-forming zone of the
consolidation structure of FIG. 4.
FIG. 6 is a logic flow diagram describing the preferred method for
forming the thermoplastic composite laminate of FIG. 1 in
accordance with FIGS. 2-5.
FIGS. 7a-7f are perspective illustration representing examples of
curved, thermoplastic composite laminate parts formed in accordance
with an embodiment of the disclosure.
FIG. 8 is a perspective illustration of a tailored, multilayer
stack of thermoplastic composite material, with three curved part
blanks cut from the stack.
FIG. 9 is a perspective illustration of tooling used to form the
curved thermoplastic composite parts in accordance with an
embodiment of the disclosure.
FIG. 10 is a perspective illustration of a curved tool used to
impart features to the curved thermoplastic composite part.
FIG. 11 is a bottom illustration of the tool shown in FIG. 10.
FIG. 12 is a fragmentary, cross sectional illustration showing a
portion of a curve composite part captured between two portions of
a tool.
FIG. 13 is an exploded, cross sectional illustration of a
thermoplastic composite I-section beam, shown in operative
relationship to tooling and machine press dies used to compact the
laminate plies.
FIG. 14 is a perspective illustration of a pre-forming structure
and a portion of a compaction press used in a method to produce
curved composite parts.
FIG. 15 is an illustration similar to FIG. 14 but showing the
opposite side of the pre-forming structure and press.
FIG. 16 is a sectional illustration, taken through the press,
showing the dies compressing the preformed part using the
consolidation tooling.
FIG. 17 is a fragmentary illustration of a section of the press,
showing a curved die in relation to tooling sleeves for producing a
part having a constant curvature.
FIG. 18 is an illustration similar to FIG. 17 but showing tooling
sleeves for producing a part having a non-uniform curvature.
FIGS. 19-23 are cross sectional illustrations of various joints
formed between a thermoplastic composite laminate and a metal
fitting.
FIG. 24 is a diagrammatic illustration of the steps used in a
method for fabricating thermoplastic composite laminates having
integrated metal fittings according to an embodiment of the
disclosure.
FIG. 25 is a cross sectional illustration of a laminate structure
having an integrated metal fitting positioned between consolidation
tooling.
FIG. 26 is a perspective illustration showing a lay-up and
consolidation tooling being fed to a continuous compression molding
machine.
DETAILED DESCRIPTION
Embodiments of the disclosure provide a novel fabrication method of
forming a thermoplastic composite ("TPC") laminate structure or
part having one or more integrated metal fittings, in a continuous
process. The TPC structures may have varying or tailored
thicknesses and/or curvature along their lengths. The embodiments
find applicable uses in a wide variety of potential applications,
including for example, in the aerospace industry. The preferred
embodiments are ideally suited for forming thermoplastic composite
stiffened members in the supporting framework of an aircraft
fuselage. Potential examples of thermoplastic composite stiffened
members include but are not limited to fuselage skins, wing skins,
control surfaces, door panels and access panels. Stiffening members
include but are not limited to keel beams, floor beams, and deck
beams.
Referring now to FIG. 1, a thermoplastic composite laminate, here a
thermoplastic composite laminate floor beam 20 having tailored and
varying thickness regions t1 and t2 is illustrated as having a web
region 22 coupled at either end to a respective pair of cap regions
24. The web region 22 and pair of cap regions 24 are formed as a
single integrated laminate structure by consolidating a pair of
non-uniform thickness tacked multi-layer ply sheet stacks 76 with a
pair of thermoplastic composite filler nuggets 26 and further with
a pair of uniform thickness tacked multi-layer ply sheet stacks 74.
Although sheet stack 76 is shown as comprising 2 plies, it is to be
understood that either of the sheet stacks 74 and 76 may include
any number of plies, depending on the application. It will also be
understood that cap regions 24, which are shown in FIG. 1 as having
a uniform thickness and one ply, may similarly be provided with
regions of varying thicknesses and/or a plurality of plies.
In alternative versions (not shown), a thermoplastic composite
laminate such as the floor beam 20 may alternatively be formed by
consolidating one or more uniform or non-uniform tacked multi-layer
ply sheets 74,76 with either one or more single ply (shown as 32 in
FIGS. 2 and 3) of a thermoplastic composite material 30, one or
more partial ply (shown as 34 in FIG. 3) of a thermoplastic
material 30, or one or more uniform or non-uniform thickness tacked
multi-layer tacked stacks 74, 76, and any combination thereof, in a
similar method to that described herein. Further, one or more
filler nuggets 26 may also be used in combination thereof to form
further alternative versions of the thermoplastic composite
laminate 20. The method for forming the thermoplastic composite
floor beam 20 as shown in FIG. 1 is described below in more detail
in conjunction with FIGS. 2-6.
The thermoplastic materials 30 used in plies 32, 34 include
thermoplastic matrix polymers (shown as 40 in FIG. 3) such as
polyetheretherketone ("PEEK"), polyetherketoneketone ("PEKK"),
polyphenylsulfone ("PPS"), polyetherimide ("PEI") preferably
reinforced with a fibrous component (shown as 38 in FIG. 3) such as
glass (s-type or e-type) or carbon fiber. The fibers 38 within each
ply 32, 34 of the thermoplastic materials 30 may be oriented in a
unidirectional or non-uniform arrangement, depending upon the
particular application. As one of ordinary skill recognizes, the
relative types, thicknesses, amounts of fibers 38 within the matrix
resin 40, as well as the type of matrix resin utilized in each ply
32, 34 may vary greatly, based on numerous factors, including cost
and the ultimate desired physical and mechanical properties of the
thermoplastic laminate composite 20. Further, the relative
orientation of the unidirectional fibers in one ply 32, 34 relative
to another ply 32, 34 may also affect the mechanical properties of
the thermoplastic composite laminate 20.
The nuggets 26 are preferably formed from a thermoplastic material
37 that is compatible with the thermoplastic material 30 via
extrusion or other well-known forming process. Preferably the
matrix resin composition 42 of the nuggets 26 is the same as the
matrix resin composition 40 of the materials 30. In addition, the
filler nuggets 26 may utilize fibers 44 similar to the fibers 38
contained within the thermoplastic material 30.
Referring now to the logic flow diagram (FIG. 6) and the processing
diagrams (FIGS. 2-5), the method for forming the TPC laminate floor
beam 20 of FIG. 1 begins in Step 150 by providing preformed plies
32, 34 of the thermoplastic materials 30 and preformed filler
nuggets 26 each retained on roller 46 or other retention
devices.
Next, in Step 160, multiple plies 32, 34 of the thermoplastic
materials 30 are stacked in a desired configuration to form either
a non-uniform thickness or uniform thickness untacked multi-layer
ply sheet stack 58 or 60 using either a hand lay-up or automated
process.
In the automated process, as shown in FIG. 2, a plurality of plies
32 or 34 (FIG. 3) of the thermoplastic material 30 are unrolled
from rollers 46 onto a conveyor table 48 to form a collated
multi-layer non-uniform thickness or uniform thickness multi-layer
ply stack 58 or 60. The rollers 46 may be situated at one end, or
along the sides of the conveyor table 48 to lay respective ply
layers 32, 34 at a particular orientation with respect to another
adjacent layer 32, 34. Thus, for example, a lower layer of a full
ply 32 may be laid having unidirectional fibers 38 extending in one
direction, while the next respective upper full ply 32 may have
unidirectional fibers 38 laid in another direction (for example, at
45 or 90 degrees relative to the underlying ply 32). A laser
projector 56 located above the conveyor table 48 ensures proper
location of the local or partial plies 34 and/or pockets 36
relative to the full plies 32.
An example of an untacked, non-uniform thickness multi-layer sheet
stack 58 made according to the process of FIG. 2 is shown in FIG.
3, which shows various full and partial plies 32, 34 and further
showing pockets 36 created between plies 32, 34. Moreover, FIG. 3
shows partial plies 62, 64 having unidirectional fibers 38 laid in
a 90-degree relative orientation with respect to one another, here
showing partial ply 62 laid in a first orientation (fibers 38
extending from front 66 to back 68), while partial ply 64 is laid
in a different orientation (fibers 38 extending from side 70 to
side 72). Of course, while not shown, plies may have fibers 38 at
other relative orientations to one another, ranging from
perpendicular to one another (i.e. a 0/90 arrangement) to parallel
with one another (i.e. a 0/0 arrangement) and every conceivable
angle there between (including, for example a 0/30 orientation, a
0/60, 0, 45, 90 orientation etc.).
Next, in Step 170, some or all of various plies 32, 34 of the
untacked stacks 58, 60 formed in FIG. 2 may be tacked together at
various predetermined locations to form either a uniform or
non-uniform thickness tacked multi-layer ply sheet stack 74, 76.
Preferably, the stacks 58, 60 are tacked together using a soldering
iron or ultrasonic welder (not shown) to form the respective stack
74, 76, although other devices used to couple together various
plies 32, 34 of thermoplastic materials known to those of ordinary
skill are also specifically contemplated. The amount and location
of tacking among the plies 32, 34 are dependent upon numerous
factors, including but not limited to the number and location of
the various plies 32, 34 and pockets 64. Moreover, the amount of
tacking should be sufficient to form a substantially integrated
tacked stack 74, 76 that can be transported as a single part.
In Step 175, the tacked stacks 74, 76 may then be cut into smaller
pieces, or are ready for use in forming the thermoplastic composite
laminates such as floor beam 20 of FIG. 1.
Next, in Step 180, a combination of at least one uniform or
non-uniform thickness tacked stack 74, 76, and at least one of
either a non-uniform thickness tacked stack 76, a uniform thickness
tacked stack 74, or a single ply 32, and optionally at least one
filler nugget 26 of thermoplastic material 30, 37 are fused
together in a consolidation structure 78 to form a single
integrated thermoplastic composite laminate such as floor beam 20.
One preferred consolidation structure 78 specifically designed to
form the thermoplastic composite laminate floor beam 20 of FIG. 1
is illustrated in FIGS. 4 and 5 below.
Referring now to FIGS. 4 and 5, the consolidation structure 78 may
include a pre-forming zone 80 and a consolidation zone 82. In the
performing zone 80, a combination of at least one uniform or
non-uniform thickness tacked stack 74, 76, optionally at least one
filler nugget 26, and at least one of either a non-uniform
thickness tacked stack 76, a uniform thickness tacked stack 74, or
a single ply 32, FIGS. 2 and 3, of thermoplastic material are
loaded in their proper orientations in a continuous process and
preformed to the desired shape at an elevated temperature to form
the preformed part 84. The preformed part 84 then exits the
performing zone 80 and enters the consolidation zone 82, wherein it
is consolidated to form a single, integrated thermoplastic
composite laminate such as floor beam 20 as described in FIG. 1
above. The elevated temperature used in performing the part should
be sufficiently high to cause softening of the tacked stacks 74, 76
or the single ply 32 so that the layers may be bent during the
performing process. However, the elevated temperature should be
below a temperature at which the polymeric component of the matrix
resin 40, 42 has the consistency of a viscous liquid.
Referring now to FIG. 5, the pre-forming zone 80 of the
consolidation structure 78 includes a pair of U-shaped tooling
channels 86 having a central portion 88 separated by a gap 90 and a
pair of side tooling sheet members 92. Sheet members 92 may also be
called mandrels 92. Preferably, the channels 86 and side-tooling
sheet members 92 are formed of materials such as stainless steel
and the like, that are capable of handling repetitious, high-heat
cycles.
A first pair 94 of tacked stacks 74 or 76 is introduced between the
respective central portions 88 and within the gap 90 of the
U-shaped channels 86. At the same time, an optional filler nugget
26 and either the additional tacked stack 74 or 76 or ply 32, are
introduced along each flange 96 of the first pair 94 and within the
respective side-tooling member 92. For the purposes of description
in the following paragraphs with respect to the illustrations of
FIGS. 4 and 5, the non-uniform thickness tacked stack 76 is shown
as the first pair 94 introduced within the gap 90. The uniform
thickness tacked stack 74 is shown being introduced at a position
between the outer portion 98 of the U-shaped channels 86 and
respective side-tooling member 92. Further, the ply layer 32 is not
depicted in this description. While not shown, the U-shaped
channels 86 include ramps and other features designed to match the
laminate thickness variations (corresponding to t1 and t2 in FIG.
1) of the particular material (here the first pair 94 of
non-uniform tacked stacks 76).
As the tacked stacks 74, 76 and nuggets 26 move through the
performing zone 80 towards the consolidation zone 82, the flanges
96 of the first pair 94 of non-uniform thickness tacked stacks 76
on either side of the u-shaped channel 86 are bent outwardly under
heat and pressure away from each other towards the respective outer
portions 98 of the U-shaped channel 86. The flanges 96 are
therefore coupled flat against the inner side of the uniform or
non-uniform thickness tacked stacks 76, with the nuggets 26 located
between the flanges 96 and the respective inner end of the uniform
or non-uniform thickness tacked stacks 76. The heat within the
pre-forming zone 80 is elevated sufficiently to allow deformation
of the flanges 96 of the non-uniform thickness tacked stacks 76,
but is below the temperature in which the polymeric component of
the matrix resin 40, 42 of the respective stacks 74, 76 and nuggets
26 has the consistency of a viscous liquid. Bending of the flanges
96 is initiated by pressure applied to the flange 96 by external
forming devices such as rollers (not shown) The side-tooling sheet
members 92 squeeze the tacked stack 74 inwardly against the flange
96, causing additional pressure to be applied to the flange 96
which aids in bending the flange 96. The preformed part 84 is then
ready to move to the consolidation zone 82.
As best shown in FIG. 4, the preformed part 84 enters a separate or
connected consolidating structure 102 within consolidation zone 82
on guide roller 105. The consolidating structure 102 includes a
plurality of standardized tooling dies generally indicated at 104
that are individually mated with the outer surfaces of the U-shaped
channels 86 and side-tooling sheet members 92. Additional details
of the tooling dies 104 will be discussed later with reference to
FIGS. 13 and 16. This commonality of the surfaces between the
standardized dies 104 of the consolidating structure 102 and the
outer surfaces of the channels 86 and sheet members 92 eliminates
the need for part-specific, costly matched dies as well as
eliminates start up times between different preformed parts having
different ply configurations.
The consolidating structure 102 has a pulsating structure 106 that
incrementally moves the preformed part 84 forward within the
consolidation zone 82 and away from the pre-forming zone 80. As the
part 84 moves forward, the part first enters a heating zone 108
that heats the part to a temperature which allows the free flow of
the polymeric component of the matrix resin 40, 42 of the stacks
74, 76 and nuggets 26. Next, the part 84 moves forward to a
pressing zone 112, wherein standardized dies 104 are brought down
collectively or individually at a predefined force (pressure)
sufficient to consolidate (i.e. allow free flow of the matrix
resin) the various plies 32, 34 of the tacked stacks 74, 76 and
nuggets 26 into its desired shape and thickness, here forming the
web region 22 and pair of cap regions 24 of the floor beam 20. Each
die 104 is formed having a plurality of different temperature zones
with insulators. The dies 104 do not actually contact the part 84,
but contact the outer surfaces of the U-shaped channels 86 and side
tooling sheet members 92 opposite the part 84. Thus, the respective
inner surfaces of the channels 86, 92 compress against the portion
of the part 84. The compression may occur wherein all of the dies
104 compress in one independent yet coordinated step. The dies 104
are opened, and the part 84 is advanced within the consolidating
zone 102 away from the pre-forming zone 80. The dies 104 are then
closed again, allowing a portion of the part 84 to be compressed
under force within a different temperature zone. The process is
repeated for each temperature zone of the die 104 as the part 84 is
incrementally advanced along the guide rollers 105 towards the
cooling zone 114.
The formed and shaped part 84 then enters a cooling zone 114, which
is separated from the pressing zone 112, wherein the temperature is
brought below the free flowing temperature of the matrix resin 40,
42, thereby causing the fused or consolidated part to harden to its
ultimate pressed shape 116. The pressed part 116 then exits the
consolidating structure 102, wherein the side sheet members 92 are
re-rolled onto rollers 120 as scrap.
While not shown, the consolidating structure 102 may have
additional parts or devices that can introduce shapes or features
into the pressed shape 116.
One preferred consolidating zone structure 102 that may be utilized
is the so-called continuous compression molding ("CCM") process as
described in German Patent Application Publication No. 4017978,
published on Sep. 30, 1993, and herein incorporated by reference.
However, other molding processes known to those of ordinary skill
in the art are specifically contemplated by the disclosure,
including but not limited to pultrusion or roll forming.
Next, in Step 190, the pressed part 116 is trimmed or otherwise
post-processed to its desired final shape to form the thermoplastic
composite laminate 20. In Step 200, the laminate 20 is inspected
visually, preferably using ultrasonic non-destructive inspection
techniques, or by other means to confirm that the laminate 20 is
correctly shaped and does not contain any visual or other defects.
After inspection, in Step 210, the laminate 20 such as the
thermoplastic composite floor beam 20 may be installed onto its
assembly. In the case of the floor beam 20, it is introduced within
an aircraft fuselage.
While embodiments of the disclosure are described in terms of
forming a thermoplastic composite floor beam 20 having essentially
an I-beam shape, other potential shapes are specifically
contemplated by the disclosure. This includes thermoplastic
composite laminates having an L-shape, a C-shape, a T-shape, or
even a flat panel shape in which thickness transitions may occur in
any section of the part. These alternatively shaped laminates, or
even other forms of the floor beam 20, are formed by consolidating
one or more uniform or non-uniform tacked multi-layer ply sheets
74, 76 with either one or more plies 32 of a thermoplastic
composite material 30, one or more partial plies 34 of a
thermoplastic material 30, or one or more uniform or non-uniform
thickness tacked multi-layer tacked stacks 74, 76, and any
combination thereof, in a similar method to that described herein.
Further, one or more filler nuggets 26 may also be used to form
additional alternative versions of the thermoplastic composite
laminates 20. To accomplish any of these alternative preferred
variations, modifications to the tooling within the pre-forming
zone 80 is necessary so as to match the desired thickness
variations for the TPC laminate 20. For example, the U-shaped tool
86 of FIG. 5 is specific for forming I-beams such as floor beam 20
of FIG. 1, an alternatively shaped tool 86 having gaps 90 is used
in forming C-shaped laminates, L-shaped laminates or flat beams
having a taper between respective ply layers. Similar to the
U-shaped tool 86, these alternative tools include regions not
contacting the stacks 74, 76 that are matched to the standardized
dies 104 within the consolidating zone 102.
While the embodiments are ideally suited for forming thermoplastic
composite laminates, by using a modified single-step consolidation
zone, thermosetting laminate composites can also be formed. In this
modified version of the consolidation process, the heating and
pressing zones achieve a temperature above the reaction or curing
temperature of the matrix resin to form a thermosetting part.
Accordingly, the single pressing process achieves a part having its
ultimate desired shape without subsequent pressing steps.
Embodiments of the disclosure provide an innovative method to
fabricate complex thermoplastic composite laminates with tailored
and varying thickness in a continuous process. This innovative
process utilizes automated equipment or hand lay-up to collate
parts or components into a multi-layer stack. Each stack contains
all plies, including ply build-up areas, tacked in the proper
location to maintain orientation and location. The consolidation
structure utilizes a two-stage method for forming the composite
laminates from the multi-layer stacks and contains all necessary
part features to achieve this result. The tooling, such as the
U-shaped tool 86 in the pre-forming zone 80 is created with an
appropriate shape to create the desired thickness variations in the
formed TPC laminates 20 and is further designed to mate with
standardized dies with the consolidation zone 82
The composite part formed by the above method may find use in a
wide variety of applications, including, for example, automotive
and aerospace applications. One example of a composite part formed
in accordance with the disclosure is ideally suited for use as
structural stiffened members, including thermoplastic composite
laminate floor beams 20, in a commercial aircraft.
Referring now to FIGS. 7-15, an alternate embodiment may be used to
manufacture thermoplastic laminate parts that are both curved and
have tailored and/or varying thickness along their length. Curved
laminates can be produced in which the curvature is either constant
(circular) or variable along the length of the laminate part. As in
the case of the embodiment previously described, the curved
thermoplastic laminate part may include tailored areas and areas of
varying thickness achieved by adding partial or local plies, or
areas containing pockets. "Tailored" or "tailoring" refers to the
profile of the part surface, wherein the selective addition or
reduction of plies in specific areas of the part can be used to
achieve a desired surface profile after the plies are consolidated
during the compaction process. Curved parts produced by this
embodiment of the method may be used in a variety of applications
such as frames, rings, formers and structural aircraft stiffened
members or fuselage skins, wing skins, door panels and access
panels, keel beams, floor beams, and deck beams. The curved parts
can be produced with a variety of cross sections, such as those
shown in FIGS. 7a-7f. A fabricated part 212 having an I-section is
shown in FIG. 7a while a part 214 having a U-section is shown in
FIG. 7b. An L-section part 216 is shown in FIG. 7c and a T-section
part is shown in FIG. 7d. A part 220 having a Z-section as shown in
FIG. 7e and a part 222 having a simple rectangular section is shown
in FIG. 7f. The parts shown in FIGS. 7a-7f may have either constant
or variable curvature as previously mentioned, and may include
areas of varying or tailored thickness at one or more points along
their lengths.
The preliminary steps in fabricating curved thermoplastic laminate
parts in accordance with this embodiment of the method are similar
to those previously described. A plurality of plies of
thermoplastic material are deposited onto a conveyor table to form
a collated, multi-layer non-uniform thickness or uniform thickness
multi-ply stack, as previously described in connection with FIG. 2.
The resulting, multi-layer stack is thus similar to the stack 58
shown in FIG. 3 which includes full and partial plies 32, 34 as
well as pockets 36 created between plies 32, 34. Partial plies 62,
64 may also be included which have unidirectional fibers 38
arranged at alternating angles relative to the direction of
orientation of the fibers. As previously described, the sheets in
the multi-layer stack 58 are tacked together using a soldering iron
or other heating device (not shown) so that the plies are held in
fixed relationship to each other. A collated, tacked stack 224
produced by the method previously described is shown in FIG. 8.
The next step in the method for producing the curved composite
parts comprises cutting individual part ply stacks or part blanks
226 from the collated stack 224. This cutting operation may be
performed, for example, by a water jet cutter (not shown) operating
under computer control which produces cut blanks 226 having an
outer profile generally corresponding to the desired part
curvature. As previously indicated, this curvature may be constant
or may vary along the length of the part blank 226.
The part blanks 226 are fed along with a later described set of
consolidation tooling 235 to a pre-forming station 275 (FIGS. 14
and 15) in a manner generally similar to that described previously
with respect to producing non-curved composite parts. In the case
of the present embodiment however, the consolidation tooling 235
and the blanks 226 move through a curved path as they are fed into
the pre-forming station 275.
The consolidation tooling 235 is shown in FIG. 9 and comprises
curved inner and outer tooling sleeves 228, 230 as well as upper
and lower tooling sleeves 232, 234. The upper and lower tooling
sleeves 232, 234 each possess a curvature corresponding to that of
the blanks 226, while the inner and outer tooling sleeves 228, 230
may be either similarly curved, or flexible so as to conform to the
curvature of the part blank 226 during the pre-forming process. In
the example illustrated in FIGS. 9, 14 and 15, the tooling sleeves
228-234 are configured to produce the Z-section part 220 shown in
FIG. 7e. Although not specifically shown in the drawings, the
part-side surfaces of the tooling sleeves 228-234 contain tooling
features that produce mirror image features in the part, such as
varying thicknesses, varying curvature, pockets, etc.
Referring now particularly to FIGS. 14 and 15, the upper and lower
tooling sleeves 232, 234 are assembled around the part blank 226
before the blank is fed in a curved path 280 into the pre-forming
station 275 which includes a plurality of forming devices 268 and a
set of guides 270. The part blank 226 can be seen to include a flat
tacked stack 262 that comprises the web 220a and cap 220b (FIG. 7e)
of the Z-section part 220, and a set of buildup plies 264 which
form a local reinforcement of the beam web 220a.
As the sandwiched assembly comprising the part blank 226 and the
tooling sleeves 232, 234 is fed into pre-forming station 275, the
inner and outer tooling sleeves 228, 230 are fed into contact with
the sandwiched assembly. Forming devices 268 function to deform
edge portions of a blank 226 against flanges 265 on tooling sleeves
232, 234, thereby pre-forming the caps 220b of the Z-section part
220. Simultaneously, additional cap reinforcement plies 266 are fed
between the forming devices 268 and the tooling flange 265. Guides
270 bring the inner and outer tooling sleeves 228, 230 into contact
with the edges of the blank 226 which form the caps 220b. The
preformed blank 226 along with the tooling sleeves 235 continue
their movement in the curve path 280 through a curved press 284
such as a CCM machine which contains dies that impose force on the
consolidation tooling 235. This force results in compaction and
consolidation of the plies of the preformed part. Although not
specifically shown in the drawings, heaters or ovens are provided
as necessary to heat the part blank 226 to a temperature at which
the polymeric component of the matrix resin in the part blank 226
has the consistency of a viscous liquid. Heating of the part blank
226 in this manner facilitates ply consolidation. In some cases,
pre-heating of the part blank 226 may also be required to
facilitate the pre-forming process. The need for pre-heating of the
part blank 226 can depend on a number of factors, such as the
number of plies, ply orientation, the type of material, the shape
being preformed, etc.
The press 284 is essentially similar to that previously described
in connection with FIG. 4. However unlike the press shown in FIG.
4, the dies used in press 284 will comprise some degree of
curvature to accommodate the curved, preformed part 226. One such
die 286 is shown in FIG. 17, where it can be seen that the inner
face 296 of the die 286 has a curvature that matches the curvature
of the flange 265 on the upper tooling sleeve 232. Die 286 moves
inwardly in the direction of the arrows 288, into contact with the
flange 265 during the compaction process, and in opposition to
another curved die (not shown) which moves into contact with the
inner tooling sleeve 228. The amount of curvature of the dies used
in press 284 will depend, in part, on the shape of the curved part
being produced and the shape of the tooling sleeves necessary for
fabrication of the features in the part. The outer face 298 of the
die 286 may be curved as shown in the FIG. 17, or may be flat. The
preformed part is moved in the curved path 280, incrementally
through the press 284. As the part movement is paused at each
incremental step, the press dies impose heat and force on the
tooling sleeves 235, resulting in consolidation of a section of the
plies that lie beneath the dies.
As previously indicated, the laminated part may have a varying,
rather than a constant curvature, along its length, and in this
connection attention is directed to FIG. 18. A die 286 used to
compact a curved preformed part 292 has a constant curved inner
face 296 which engages the outer face 300 of a tooling sleeve 290.
The outer face 300 of tooling sleeve 290 has a constant curvature,
matching the curvature of the inner face 296 of the die 286, but
has an inner face 302 that is curved with a radius different than
that of the outer face 300 of the tooling sleeve 290, resulting in
a part 292 having a non-constant outer radius.
Another example of a curved thermoplastic laminate part 236 is
shown in FIGS. 10 and 11 wherein the part has curvature over its
length and has a body 238 which is U-shaped in cross section. The
body 238 has a pair of sloped ramps 240 which form transitions in
the thickness of the body 238 so that the part 236 has 3 sections
of different thicknesses along its length. In addition, the top
side of the body 238 is provided with a pocket or depression 242
representing an area of reduced thickness in the part 236. The
differing thicknesses of the body 238 are represented by t.sub.1,
t.sub.2, t.sub.3, while the thickness of the pocket 244 is
represented by t.sub.4. Although part 236 possesses constant inner
and outer curvatures, it is to be understood that the curvature may
vary along the length of the part 236.
FIG. 12 shows a portion of the part 236 held within tooling sleeves
246, 280 for consolidating the part plies. The part plies 236 can
be seen to have a ply buildup area 252 which effectively increases
the thickness of the body 238, and results in the slope 240. The
tooling sleeves include a release coated metal shim 246 and an
outer consolidation tool portion 248 having a ramp for forming the
slope 240. As viewed in FIG. 12, the top side of the tooling sleeve
248 is flat so as to be engageable with a universal die, such as
any of the dies 256 shown in FIG. 13.
FIG. 13 shows another example of a curved part 212 fabricated in
accordance with the disclosed embodiments. Part 212 comprises a
curved beam having an I-shaped cross section. Conventional machine
dies 256 can be used to consolidate parts that have both curvature
and varying thickness along their length. In this example, the
tooling sleeves comprises a pair of flat metal sheets or shims 260
and a pair of tooling sleeves 258 that are generally U-shaped in
cross section. The flat sheets 260 assist in forming the caps of
the part 212 while sleeves 258 function to form portions of the cap
as well as the web of the part 212. The faces of the sleeves 258
that face the part 212 may have tooling features such as raised
areas or ramps that impart mirror image features onto the part 212.
Although not specifically shown in FIG. 13, the sheets 260 and
tooling sleeves 258 may be curved along their length in order to
form a part 212 that is also curved.
In some cases, it may be desirable to integrate one or more metal
fittings into any of the TPC laminate structures described above,
including those that have curvature along the length and/or
tailored or varying laminate thickness. Potential applications of
TPC laminate structures having integrated metal fittings includes
beams, stanchions, frames, rings, formers, skins and other
structural stiffening members. In accordance with embodiments of
the disclosure, metal fittings can be integrated into the
previously described TPC laminate structures as part of a
continuous process for fabricating these structures, as previously
discussed.
Referring now to FIGS. 19-23, a metal part or fitting such as the
metal fitting 304 shown in FIG. 19 may be bonded and integrally
formed with a TPC laminate structure 306 according to a method
which will be discussed below in more detail. The TPC composite
material in structure 306 may comprise, for example without
limitation, AS4D/PEKK. The metal fitting 304 may be formed from any
suitable material, depending upon the application such as, without
limitation, aluminum or titanium. The metal fitting 304 may have
any of various geometries and features depending on the application
and purpose of the fitting 304. In the case of the application
shown in FIG. 19, the metal fitting at 304 acts as a "doubler"
which reinforces a location section of the TPC laminate structure
306.
FIG. 20 illustrates a double lap splice 316 between two TPC
laminates 312, 314. A pair of metal fittings 308, 310 are
integrally bonded to opposite sides of laminates 312, 314,
overlying the splice joints 316.
FIG. 21 illustrates the use of a scarf joint 322 between a TPC
laminate 320 and a metal fitting 318.
FIG. 22 illustrates a stepped lap joint 328 between a metal fitting
324 and a TPC laminate 326. The metal fitting 324 includes a series
of symmetrical steps 325 along one edge thereof, which
complementally receive one or more individual plies 327 of the
laminate 326.
FIG. 23 illustrates a rabbet joint 334 formed between a metal
fitting 330 and a TPC laminate 332.
The joints illustrated in FIGS. 19-23 are merely representative of
a wide range of joint constructions and geometries that may be used
in carrying out the embodiments of the disclosure.
Referring now to FIGS. 24-26, a method continuously fabricating TPC
laminate structures or parts having integrated metal fittings
begins with the provision of raw materials and parts, shown in FIG.
24 as "Step A". The materials include a fiber reinforced composite
material 338 with PEKK (Polyetherketoneketone) as the matrix resin
(or other TPC composite material), PEKK film 340 and metal fittings
336. The reinforced composite material 338 may be in unidirectional
or fabric prepreg forms. The metal fittings 336 may be machined
from titanium or other suitable metals. The fittings 336 are
cleaned and a high temperature bonding primer is applied to the
bonding surfaces on the fittings 336. Additional components (not
shown), such as the filler nuggets 26 (FIG. 5) used in
manufacturing the I-beam shown in FIG. 1, are extruded or molded
into discrete lengths.
Next, at "Step B", a lay-up 345 is prepared, comprising metal
fittings 342, 343, 350, multiple TPC plies 346, and layers 344, 348
of PEKK film. A layer 340 of the PEKK film is applied to the primed
bonding surfaces of the metal fittings 342, 343 and 350. Depending
upon the type of joint and the particular application, an automated
process or hand lay-up may be used to create customized stacks
comprising multiple plies 346 of the reinforced composite materials
from the supply of material 338, which may be in spool form. The
automated process, which has been previously described, produces
material blanks for multiple parts or components for a wide variety
of lay-up configurations. The plies 346 in the stack may be tacked
together in multiple locations using a heating or ultrasonic
welding device as previously described. In the particular
embodiment shown in FIG. 24, fittings 342, 343 are joined to the
ends of the stack of plies 346 using any of the joints shown in
FIGS. 20-23 (or other joint configurations), and the metal fitting
350 is positioned on top of the plies 346 and acts as a doubler in
the finished part.
The lay-up 345 is positioned between consolidation tools 352 of the
type previously mentioned, as shown in "Step C" in FIG. 24. The
consolidation tools 352 may include surface features that are
transferred to the laminate plies 346 in order to create thickness
tailoring, thickness variations and curvatures or other part
features. These part features may include pockets to accommodate
features of the fittings 342, 343 and 350, as well as ply buildup
ramps, part curvatures, etc. The sides of the tool 352 which mate
with a CCM machine 368 is of a constant size and shape to match
standard dies on the CCM machine 368. The locations of the features
on the tools 352 are coordinated with the features of the stack of
plies 346. Thin steel sheets (not shown) of the type previously
described, may be used on the non-tool side of the lay-up 346.
"Step D" in FIG. 24 and FIG. 25 better illustrate the relationship
between the tools 352 and the lay-up 345. The consolidation tools
352 include tool members 358, 360 engaging opposite sides of the
lay-up 345. The tool members 358, 360 are engaged by press platens
354, 356 which squeeze the tool members 358, 360 together in order
to consolidate the plies 346 lay-up 345. One of the tools 358
includes a pocket having a shape matching that of the doubler
fitting 350. The second tool member 360 is smooth on both of its
opposite faces.
As shown in FIG. 26, the lay-up 345 is fed along with the tool
members 358, 360 into the CCM machine 368, in the direction of the
arrow 347. Although not specifically shown in FIG. 26, the lay-up
345 along with the consolidation tool members 358, 360 may pass
through a pre-forming station such as that shown in FIG. 5, where
the lay-up 345 is preformed into the approximate shape of the final
part 366.
The CCM machine 368 consolidates the lay-up 345, including fittings
342, 343, 350, into a solid, monolithic part. The lay-up 345 and
consolidation tooling 352, are continuously moved, incrementally
through the CCM machine 368 so that press platens 354, 356 apply
pressure to successive sections of the tooling 352 as the lay-up
345 is moved each incremental step. It should be noted here that
other consolidation processes may be used, such as those employing
heated presses (not shown).
As shown in FIG. 24 at "Step E", following consolidation, the
tooling 352 is removed from the consolidated part 366 and the part
366 is trimmed. At step "F", the part 366 is inspected, using
nondestructive inspection techniques. The final part 366 shown in
"Step G" is a monolithic, fully consolidated structure in which the
metal fittings 342, 343 and 350 are formed integral with the
consolidated plies 346 of the TPC laminate.
Although the embodiments of this disclosure have been described
with respect to certain exemplary embodiments, it is to be
understood that the specific embodiments are for purposes of
illustration and not limitation, as other variations will occur to
those of skill in the art.
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